Method and apparatus for controlling the drying and cooling of field-harvested seeds in storage

• US 4,800,653 A
• Filed: 08/17/1979
• Issued: 01/31/1989
• Est. Priority Date: 06/30/1977
• Status: Expired due to Term

• Current Assignee: Sylvester L. Steffen
• Original Assignee: Sylvester L. Steffen
• Inventors: Steffen, Sylvester L.
• Primary Examiner(s): Bennet, Henry A.
• Application Number:
  US06/067,347
• Time in Patent Office: 3,455 Days
• Field of Search: 34/26, 34/28, 34/30, 34/46, 34/48, 34/230, 34/233, 219/368, 21/92, 426/236, 426/465, 98/55
• US Class Current: 34/495
• CPC Class Codes: F26B 23/04 using electric heating F26B23/10 takes precedence
• CPC Class Codes: F26B 9/063 for drying granular material in bulk, e.g. grain bins or silos with false floor shallow layer rotary sweep drying bins F26B9/10; perforated wall silos with drying air channels in the stack F26B9/103

Abstract

Method and apparatus for conditioning and preserving living seeds in a bin of the type having means for forcing air into a plenum chamber in the lower part of the bin, a floor pervious to gas flow forming the top of the chamber, and heating means. Electrical heating means such as heat lamps are utilized to introduce energy into the plenum air. A variation is disclosed wherein the heating means and plenum chamber are located in the upper part of the bin, and the air flow is from top to bottom.

The process involves measuring the temperature of drying air in the plenum chamber, measuring the temperature of exhaust air leaving the bin, and inactivating the heating means when the difference between the two temperatures exceeds a predetermined level. Energy is introduced into the plenum-air to supplement the air'"'"'s natural capacity for holding moisture; a temperature sensing element in the exhaust-air activates or deactivates the energy sources according to a pre-selected (manual or automatic) allowable temperature depression that occurs from evaporative cooling. The differential setting is selectively controllable to accommodate the hygroscopic properties of differing seeds and variations of seasonal temperatures and humidities.

Claims

1. The process of drying and preserving seeds in a bin having heating means and means for forcing air into a plenum chamber in the lower part of the bin, said heating means being disposed in said plenum chamber, the chamber being covered by a floor pervious to gas flow, the process comprising the steps of:

introducing atmospheric air into the plenum chamber;

determining the temperature within the plenum chamber;

determining the temperature of exhaust air leaving the bin;

inactivating the heating means when the temperature of the air in the plenum chamber minus the temperature of the exhaust air is greater than a pre-selected amount; and

controlling the amount of heat from said heating means to always maintain the exhaust air temperature cooler than the inlet air temperature while the grain is curing.

2. A grain drying bin as defined in claim 1 including:

means for determining the temperature of air in the plenum chamber;

means for determining the temperature of air as it exhausts the bin;

thermostat means responsive to the temperature of the air in the plenum chamber for controlling the operation of the heating means; and

means adapted to override the thermostat controlling the heating means and inactivate the heating means when the temperature difference between the drying air in the plenum chamber and the air exiting the bin is greater than a predetermined amount.

3. A grain drying bin as defined in claim 2 including:

a plurality of heat lamps spaced about the bin wall adjacent the plenum chamber and having a total output of 10 to 40 watts per one hundred bushels of bin capacity.

4. A grain drying bin as defined in claim 3 including:

a plurality of fans distributed about the wall of the plenum chamber;

each fan being individually controlled and including closure means to prevent air from exiting the plenum chamber when the fan is inactivated.

5. A grain drying bin as defined in claim 4 including transparent heat lamp mounting plates detachably secured to the bin wall.

6. A grain drying bin as defined in claim 2 including means for indicating the amount of air being introduced into the plenum chamber.

7. A grain drying bin of the type having a plenum chamber formed in the lower part thereof and a gas-pervious floor forming the top of the plenum chamber including:

means for introducing atmospheric air into the plenum chamber;

heating means for adding heat energy to the air in the plenum chamber;

means for sensing the temperature of air in the plenum chamber;

means for sensing the temperature of air as it exhausts the bin;

thermostat means for controlling the operation of the heating means; and

differential temperature control means adapted to override the thermostat means controlling the heating means and thereby inactivate the heating means when the temperature difference between the drying air in the plenum chamber and the air exiting the bin is greater than a predetermined amount.

8. A grain drying bin as defined in claim 7 including means for indicating the temperature of the air in the plenum chamber and means for indicating the temperature of the air exiting the bin.

9. A grain drying bin as defined in claim 7 wherein the means for introducing atmospheric air operates at approximately 1.5 to 9.0 cubic feet per minute per bushel of grain at moistures between 18 and 30 grain percent moisture.

10. A grain drying bin as defined in claim 7 including:

a control panel;

means mounted on the control panel for continuously indicating the temperature of the air in the plenum chamber;

means mounted on the control panel for continuously indicating the temperature of the air exiting the bin;

adjustable means mounted on the control panel for controlling the thermostat means; and

adjustable means mounted on the control panel for controlling the temperature control means.

25. A grain drying bin as defined in claim 7 wherein said temperature differential is determined by subtracting the temperature of the exiting air in the exhaust chamber from the higher temperature of the inlet air in the plenum chamber.

11. In a grain drying bin of the type having a first chamber formed in the lower part thereof, a gas-pervious floor forming the top of said first chamber, and a second chamber formed between the grain and the top of the grain bin, one of said chambers being an exhaust chamber, the improvement comprising:

means for introducing atmospheric air into the plenum chamber;

heating means for adding heat energy to the air in the plenum chamber;

means for sensing the temperature of air in the plenum chamber;

means for sensing the temperature of air in the exhaust chamber;

thermostat means operating in response to the temperature of air in the plenum chamber for controlling the operation of the heating means by activating the heating means when the temperature of the air in the plenum chamber is below a predetermined temperature and inactivating the heating means when the temperature of the air in the plenum chamber is above said predetermined temperature;

differential temperature control means operating in response to the difference in temperature between the air in the plenum chamber and the air in the exhaust chamber for overriding the activation of the heating means by the thermostat means when said difference in temperature exceeds a predetermined temperature amount to thereby inactivate the heating means only while the difference in temperature exceeds said predetermined temperature, said differential control temperature means having no overriding effect on the thermostat means when said difference in temperature does not exceed said predetermined temperature.

12. A grain drying bin as defined in claim 11 including means for indicating the temperature of the air in the plenum chamber and means for indicating the temperature of the air in the exhaust chamber.

26. A grain drying bin as defined in claim 11 whereby said temperature differential is determined by subtracting the temperature of the exiting air in the exhaust chamber from the higher temperature of the inlet air in the plenum chamber.

13. In a grain drying bin of the type having a first chamber formed in the lower part thereof, a gas-pervious floor forming the top of said first chamber, and a second chamber formed between the grain and the top of the grain bin, one of said chambers being a plenum chamber and the other of said chambers being an exhaust chamber, the improvement comprising:

means for introducing atmospheric air into the plenum chamber;

heating means for adding heat energy to the air in the plenum chamber;

electric circuit means for controlling the heating means;

means for sensing the temperature of air in the plenum chamber;

thermostat means for opening or closing the circuit means in response to the temperature of air in the plenum chamber to thereby activate the heating means as long as the air in the plenun chamber is below a predetermined temperature; and

differential temperature control means set at a predetermined temperature differential between the plenum air and the exhaust air for automatically opening the circuit means of the heating means when the predetermined temperature differential is exceeded and closing the circuit means when the differential temperature is less than the predetermined temperature differential setting.

14. A grain drying bin as defined in claim 13 including means for indicating the temperature of the air in the plenum chamber and means for indicating the temperature of the air in the exhaust chamber.

27. A grain drying bin as defined in claim 13 whereby said temperature differential is determined by subtracting the temperature of the exiting air in the exhaust chamber from the temperature of the inlet air in the plenum chamber.

15. In a grain drying bin of the type having a first chamber formed in the lower part thereof, a gas-pervious floor forming the top of said first chamber, and a second chamber formed between the grain and the top of the grain bin, one of said chambers being a plenum chamber and the other of said chambers being an exhaust chamber, the improvement comprising:

means for introducing atmospheric air into the plenum chamber;

heating means for adding heat energy to the air in the plenum chamber;

means for sensing the temperature of air in the plenum chamber;

means for sensing the temperature of air in the exhaust chamber;

first thermostat means operating in response to the temperature of air in the plenum chamber for activating the heating means so long as the air in the plenum chamber is below a predetermined temperature; and

second thermostat means operating in response to the temperature of air in the exhaust chamber for further controlling the heating means by automatically overriding the first thermostat means by preventing the operation of the heating means when the temperature of the air in the exhaust chamber is below a predetermined temperature, said predetermined temperature of said first thermostat means being higher than said predetermined temperature of said second thermostat means.

16. A grain drying apparatus as defined in claim 15 wherein said heating means is an electrical heating means.

17. A grain drying apparatus as defined in claim 16 wherein said electrical heating means has a total wattage of 10 to 40 watts per one hundred bushels of grain capacity.

18. A grain drying apparatus as defined in claim 16 wherein said electrical heating means comprises at least one heat lamp.

19. A grain drying apparatus as defined in claim 16 wherein said electrical heating means comprises a plurality of heat lamps.

20. A grain drying apparatus as defined in claim 19 wherein said means for introducing atmospheric air into the plenum chamber comprises a plurality of fans spaced about the plenum chamber.

21. A process for curing seeds comprising:

placing uncured seeds in a closed environment;

adding atmospheric air to one point of the closed environment, and allowing air to exit at another point in the closed environment;

maintaining the addition of atmospheric air within specified quantities;

measuring the temperature of the air at the point of entry of the atmospheric air and at the point of exhaust from the closed environment;

adding heat to the entering atmospheric air only when the temperature difference between the entering air minus the exiting air is less than a predetermined amount;

controlling the amount of such heat being added to thereby always maintain the temperature of the exiting air cooler than the temperature of the entering atmospheric air; and

continuing the addition of atmospheric air and controlling the addition of heat to the atmospheric air until a desired equilibrium moisture has been achieved in the stored seeds.

22. A process as defined in claim 21 wherein the desired equilibrium moisture is at 18 percent and the temperature of the seeds are at 40°

F.

31. A method of curing and drying food-seeds as defined in claim 21 wherein:

said step of continuing the addition of atmospheric air for bringing the foodseeds into an equilibrium moisture with atmospheric air, results in the moisture content of the seeds not being reduced to levels below that which is seasonally normal from exposure to atmospheric air, and whereby the temperature of the seeds is not raised to levels above the seasonal normal of atmospheric temperatures.

23. A process of drying uncured seeds comprising the steps of:

placing uncured seeds in a closed environment;

adding atmospheric air to one point of the closed environment, and allowing air to exit at another point in the closed environment;

determining the temperature of the air at the point of entry into the seeds;

determining the temperature of the air at the point of exhaust from the seeds;

adding heat to the entering atmospheric air only when the difference between the temperatures of the entering air minus the exiting air is less than a predetermined amount required to achieve a desired equilibrium moisture in the stored seeds; and

controlling the amount of such heat being added to thereby always maintain the temperature of the exiting air cooler than the temperature of the entering atmospheric air.

24. In a grain drying bin of the type having a first chamber formed in the lower part thereof, a gas-pervious floor forming the top of said first chamber, and a second chamber formed in the top of the grain bin, one of said chambers being a plenum chamber and the other of said chambers being an exhaust chamber, the improvement comprising:

means for introducing atmospheric air into the plenum chamber;

heating means for adding heat energy to the air in the plenum chamber;

means or sensing the temperature of the air in the plenum chamber;

means for sensing the temperature of the air in the exhaust chamber; and

differential temperature control means operating in response to the difference in temperature between the air in the plenum chanber and the air in the exhaust chamber for activating the heating means when the result of the temperature in the plenum chamber minus the temperature in the exhaust chamber is a predetermined amount or less, and deactivating the heating means when the result of the temperature in the plenum chamber minus the temperature in the exhaust chamber is greater than said predetermined amount.

28. In a grain bin of the type having a first plenum chamber formed in the lower part thereof, a gas-pervious floor forming the top of said first chamber, and a second exhaust chamber formed in the top of the grain bin, the improvement comprising:

means for bringing atmospheric air from the outside of said bin into said plenum chamber and causing said air to move successively from the outside of the bin, through the plenum chamber, through the floor, through the grain, through the exhaust chamber and out of the exhaust chamber to atmosphere;

heating means for adding heat energy to the air in said plenum chamber;

means for sensing the temperature of air at a first point prior to the entry of such air into the grain;

means for sensing the temperature of the air at a second point after it has passed through the grain in said exhaust chamber; and

differential temperature control means operating in response to the difference in temperature between the air at the first point and the air at the second point for activating said heating means when the result of the temperature at the first point minus the temperature at the second point is a predetermined amount or less, and for deactivating said heating means when the result of the temperature at the first point minus the temperature at the second point is greater than said predetermined amount.

29. A process of drying and preserving seeds, said seeds being in a bin having heating means and means for forcing air from outside of the bin into a plenum chamber in the lower part of the bin, said heating means being disposed in said plenum chamber, said plenum chamber being covered by a floor pervious to gas flow, said process comprising the steps of:

introducing atmospheric air into said plenum chamber;

determining the temperature of the incoming air at a first point prior to its entry into the grain;

determining the temperature at a second point of exhaust air leaving the grain;

inactivating said heating means when the temperature of the air at the first point minus the temperature at the second point of the exhaust air is greater than a pre-selected amount; and

controlling the amount of heat from said heating means always to maintain the exhaust air temperature at the second point cooler than the inlet air temperature at the first point while the grain is curing.

30. A process of drying uncured seeds comprising the steps of:

placing uncured seeds in a closed environment;

adding atmospheric air to one point of the closed environment, and allowing air to exit at another point in the closed environment;

determining the temperature of the entering air prior to the entry of such air into the seeds;

determining the temperature of the air exiting from the seeds;

adding heat to the entering atmospheric air only when the difference between the temperatures of the entering air minus the exiting air is less than a predetermined amount required to achieve a desired equilibrium moisture in the stored seeds; and

controlling the amount of such heat being added whereby the temperature of the exiting air is cooler than the temperature of the entering atmospheric air.

32. A method of curing and drying food-seeds in a storage bin of a type having a first plenum for introducing atmospheric air into a mass of stored grain and a second plenum for receiving the exiting air, fan ventilation means, temperature sensing means in the first plenum and temperature sensing means of the grain/air at the exiting surface of the food-seeds, said method comprising:

activation of said fan ventilation means for bringing the food-seeds into an equilibrium of temperature and moisture with atmospheric air, whereby the moisture content of the seeds is not reduced to levels below that which is seasonally normal from exposure to atmospheric air, and whereby the temperature of the seeds is not raised to levels above the seasonal normal of atmospheric temperatures, the progress of curing and drying being monitored by means of sensing atmospheric wet-bulb-depressions which indicate the equilibrium moisture being obtained in the seeds and which control a heating means to prevent wet-bulb depressions from occurring in the stored seeds which are greater than seasonal normals of atmospheric air.